On Sun, 11 Dec 2005, Brian van den Broek wrote:
> I have a case like this toy code:
>
> import random
> list1 = [1,2,3]
> list2 = ['a', 'b', 'c']
> item = random.choice(list1 +list2)
> if item in list1:
> others = list2
> else:
> others = list1
Hi Brian,
This code works, and as long as you give it a good function name, I think
it's fine the way it is.
If we're concerned with efficiency, we might want to change the
random.choice() call to a random.randrange(), to avoid building the
concatenation of list1 and list2. This looks like:
####
def sampleFromTwoLists(list1, list2):
"""Given two lists, returns a random element out of one of the lists
as well as the other list."""
index = random.randrange(len(list1) + len(list2))
if index < len(list1):
return list1[index], list2
else:
return list2[index - len(list1)], list1
####
Just out of curiosity, are you planning to do some kind of stratified
sampling with this?
> Another way occurred to me, but I wonder if I'm being too cute:
>
> item = random.choice(list1 +list2)
> others = [list1, list2][item in list1]
Too cute. *grin* Although it's concise, I'm having a hard time reading
it.
Talk to you later!
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